Preludes from files prevent processing of main file

[bclement-ocp]

When using preludes from a File` source, processing stops after the first prelude. Preludes from a Raw` source work as expected.

This seems to be due to the following code that forcefully adds exit statement when parsing a file.

[Gbury]

Any idea why the tests in tests/cram.t/run.t do not catch the error ? these tests should exercise the case where there is a prelude, and there is an error in the "main" file

[bclement-ocp]

As discussed privately, this seems to be because Dolmen ignores ``Exit` statements, while solvers are expected to quit when encountering them.